Hub construction for boat propellers



March 7, 1967 o. L. BIHLMIRE 3,307,634

HUB CONSTRUCTION FOR BOAT PROPELLERS Filed Jan. 17, 1966 United StatesPatent 3,307,634 HUB CONSTRUCTION FOR BOAT PROPELLERS Otto L. Bihlmire,115 W. Pendle St., South Bend, Ind. 46637 Filed Jan. 17, 1966, Ser. No.521,125 Claims. (Cl. 170-160.54)

My invention relates to boat propellers, and more particularly to thehubs thereof. A frequent hazard in the operation of boat propellers isthe impact of the propeller with an underwater obstruction, such as areef, sand bar, projecting rock or root. When a propeller blade of metalor other rigid material strikes such an obstruction, one' possibility isthat the blade may break or crack; another is that it will transmit theshock to the motor drive and cause injury to the same. Yieldable bladeshave been used in order to avoid the situation just described. Thus, theimpact of such a blade with an unyielding obstruction is that the bladewill either bend or break off. In either case the boat drive will becomeunbalanced and jerky. A still further effort has been made to conservethe propeller and boat drive, that is, by locating :a yieldable elementin the hub of the propeller. Thus, a rubber bushing, bonded to the metalor other material of the propeller hub was incorporated in the same. Inthis case, when the propeller struck an immovable obstruction, thebushing in the hub would yield, protecting the blades and drive gearfrom injury. When such an incident occurs the propeller will stop, butits center drive will continue, breaking up and pulverizing the rubberbushing. Now, should the boat be backed away from the obstruction, theshaft drive would continue, but without turning effect on the propeller,The boat would thus be stranded, and the use of oars or the handsrequired in order to bring the boat to a landing facility. Moreover,where the water is rough, the boat may capsize with loss of life.

In view of the above situation, it is one object of the presentinvention to employ a yieldable element in a propeller hub in a mannerto restore the hold by the power drive on the propeller after the latterhas been freed from an obstruction, in order that the propeller maycontinue to turn and keep the boat in motion.

A further object is to mount a yieldable bushing in a propeller hub withmeans to restore the effectiveness of the bushing after it has beendisrupted, and render it sufficiently firm to transmit the power driveto the propeller.

Another object is to construct the propeller hub with automatic clutchor take-up means, effective to pack the hub bushing into the firm statenecessary to transmit the power drive as stated.

A better understanding of the invention may be gained by reference tothe accompanying drawing, in which:

FIG. 1 is a view of the improved propeller as mounted on a drive shaft,and from the rear;

FIG. 2 is an enlarged longitudinal section of the hub portion of thepropeller, with parts in elevation;

FIG. 3 is a section on the line 33 of FIG. 2; and

FIG. 4 is a duplication of the center portion of FIG. 3, showing amodification.

Referring specifically to the drawing, denotes the drive shaft, 11 thehub, and 12 the blades of the boat propeller. The hub and blades arepreferably molded in one piece from hard plastic material with aflexible factor in the blades, so that these may yield to minorobstructions.

The propeller is assembled by receiving a massive sleeve 15 inside itshub. At the front end-when the propeller is installed behind a boat-thesleeve 15 has a conventional screw thread 15b suitable for receiving anut 16, the latter having notches 16a in its front end for theappliation of a spanner wrench to turn the nut. Before its Patented Mar.7, 1967 rear end the sleeve is again threadedas indicated at 15cbut inthe opposite direction, the thread being known as a left-hand one. A nut17 of the corresponding type, but smaller than the nut 16, is providedfor mounting on the thread 15c, and has notches 17a in its rear end likethe nut 16. The middle part of the sleeve is hexagonal in cross-section,and the main form thereof has a series of longitudinally-directedgrooves 15a.

The hub of the propeller has an axial opening whose frontal portion isindicated at 11a and so positioned when the propeller is mounted behinda boat. The portion 114 recedes with a conical cavity 11b in rearwarddirection to form a rearwardly-facing annular shoulder near the end ofthe hub; and the rear portion lid 11d of the opening meets the shoulderfrom the rear. The wall of the hub cavity 11b has a series oflongitudinal ribs He in circular sequence.

The yieldable bushing for the hub 11which may be of rubber or the toughplastic substance known as neopreneis shown at 20. The form of thebushing is conical to conform with that of the hub cavity 11b; and theperiphery of the bushing is grooved at 20a to conform with the series ofcavity ribs He. The interior of the main form of the bushing has aseries of longitudinallydirected ribs 201: conforming to the grooves 15aof the sleeve 15. However, the sleeve and bushing may be joinedsufiiciently without the need of the co-acting ribs 20b and grooves 15a,and such a modification is illustrated in FIG. 4. The propeller isassembled by first mounting the nut 16 on the sleeve from the front, andsliding the bushing on the sleeve from the rear until the bushing meetsthe nut 16 as a backing. The position of the nut 16 is where it may beadjusted back or forth if desired until its position is consideredpermanent. The hexagonal fit between the sleeve and the bushing engagesthese parts for joint rotation; and the internal ribs 20b of the bushingprocure a keyed relation with the grooves 15a in the sleeve. Also, broadsurface contact is present between the bushing and the larger-sized nut16. The sleeve with the bushing mounted as stated is now inserted intothe hub cavity 11b in a manner to project the rear end of the sleevethrough the rear opening portion 11d as shown in FIG. 2. A yieldablewasher 22 is now inserted in the said rear opening portion to seatagainst the shoulder 11c of the bushing, the washer followed by mountingand advancing the rear nut 17 on the thread of the sleeve. This actionwill cause the frontal nut 16 to seat the bushing snugly in the hub in amanner to transmit a rotary drive from the sleeve to the hub; and thedegree to which the bushing is compressed is regulated by adjusting therear nut 17. When the internal parts have been assembled with the hub asstated, the propeller is ready for mounting on the shaft 10 as shown inFIG. 2; and it is made fast thereon by a shear pin 15d.

The threading function of the nuts 16 and 17 will now be explained. Aspreviously mentioned, the front end of the sleeve 15 has a regular orright-hand thread; and the rear nut 17 may be advanced against thewasher 22 to make the hub bear against the bushing with compressingeffect; and the nut 16 may also be adjusted to locate the bushingproperly for this purpose. The shaft 10 is designed to rotate incounterclockwise direction as seen from the rear, in which event anyfurther tendency of the rear nut 17 to turn will cause it to over-runthe sleeve and advance against the bushing because of the left-handthread on the rear end of the sleeve, increasing the compression of thebushing.

As will now be evident, the motion of the drive shaft will betransmitted by the bushing to the propeller to operate the boat undernormal conditions; and this will prevail despite minor obstructionsbecause of the yielding of the propeller blades to by-pass them, asmentioned before. However, in case an unyielding obstruction isencountered the propeller is stopped, but the bushing will yield to thedriving force of the shaft to save the motor and drive gearing fromshock or injury. This action has a disruptive effect on the surfaceportion of the bushing, so thatwhen the boat is pushed or backed awayfrom the obstructionthe bushing Will have a reduced or minimalsub-stance for driving the propeller. However, the nut 17 may beadvanced manually with added compressing and packing effect on thebushing as stated before, so that the bushing will become sufficientlysolidified to resume its function as a clutch and procure the normaloperation of the propeller. Or, if it is not practicable to advance thenut 17 manually, a quick speed-up of the engine will have an advancingeffect on the nut to again engage the clutch.

In conclusion, it will be apparent that the bushing in the novel hubconstruction does not have to be bonded or otherwise mounted permanentlyon the hub of the propeller. The latter is complete as a unit whenassembled with its internal parts, and therefore in readiness to bemounted on a shaft of the proper size whenever needed. Further, theclutch will not require the services of a repair man in case thepropeller becomes loosened from the shaft because of striking a majorobstruction during its travel, as the simple manual take up of the nut17 or the quick acceleration of the engine will -re-pack the yieldablesubstance of the bushing and solidify the same to a sufficient degreefor transmitting the shaft drive to the propeller. A facility is thusprovided which enables the occupants of a boat to procure a quickrestoration of its drive by merely backing the boat away from theobstruction and imparting either of the adjustments mentioned, so thatthe boat may proceed on its course and avoid the hazards of beingstranded or capsizing in a rough sea.

I claim:

1. A marine propeller drive shaft clutch comprising in combination withthe propeller hub:

(a) the hub having an axial opening therethrough the normally forwardend portion of which is tapered inwardly;

(b) a sleeve within and longitudinally of the axial opening;

(c) an elastomeric bushing on an intermediate portion of the sleevewithin said tapered end portion of the axial opening in juxtaposed andbearing engagement with the adjacent hub walls;

(d) a nut threadedly engaged with the normally forward end portion ofthe sleeve, received within said opening .for adjustable bearingengagement with and on the adjacent end of said bushing, and,

(e) a second nut threadedly engaged on the opposite end portion of saidsleeve, received within said opening for adjustable bearing engagementwith and on the remaining and adjacent end of the hub.

2. The structure of claim 1 further characterized in that said one endportion of the opening is formed with an inwardly tapering wall and thebushing is of inwardly tapering form and size substantiallycorresponding to said one end portion of the opening.

3. The structure of claim 1 further characterized in that said one endportion of the opening is for-med with an inwardly tapering conicalwall, and the form of the bushing substantially corresponds in shape andsize to that of the one end portion of the opening.

4. The structure of claim 1 further characterized in that the normallyforward portion of the hub axial opening is of inwardly tapering conicalshape, and the form of the bushing is of shape and size substantiallycorresponding to that of said forward portion of the opening, andfurther characterized in that the threadson the normally forward endportion of the sleeve are of the left-hand type whereby to cause thefirst mentioned nut to overrun the shaft when said shaft is given anaccelerated rotative impulse and render the adjustability of the nutautomatic.

5. A marine propeller drive shaft clutch comprising in combination withthe propeller hub:

(a) the hub having an axial opening therethrough, the

intermediate portion of which is tapered toward the normally rearwardend of the hub, thickening and reinforcing the hub walls intermediatelyof the opopening for adjustable bearing engagement with and on theadjacent end of said bushing, and,

(e) a second nut threadedly engaged on the opposite end portion of saidsleeve received within said opening for adjustable bearing engagementwith and on said internal shoulder of the hub.

References Cited by the Examiner UNITED STATES PATENTS 1,493,066 5/1924Caldwell et a1. 170-16054 2,543,396 2/1951 Wolff l-135.75 2,569,1449/1951 Benson l35.75 3,047,074 7/1962 Rielag 170160.54 3,224,509 12/1965Thompson l70l60.5

MARTIN P. SCHWADRON, Primary Examiner. EVERETTE A. POWELL, .TR.,Examiner.

1. A MARINE PROPELLER DRIVE SHAFT CLUTCH COMPRISING IN COMBINATION WITHTHE PROPELLER HUB: (A) THE HUB HAVING AN AXIAL OPENING THERETHROUGH THENORMALLY FORWARD END PORTION OF WHICH IS TAPERED INWARDLY; (B) A SLEEVEWITHIN AND LONGITUDINALLY OF THE AXIAL OPENING; (C) AN ELASTOMERICBUSHING ON AN INTERMEDIATE PORTION OF THE SLEEVE WITHIN SAID TAPERED ENDPORTION OF THE AXIAL OPENING IN JUXTAPOSED AND BEARING ENGAGEMENT WITHTHE ADJACENT HUB WALLS; (D) A NUT THREADEDLY ENGAGED WITH THE NORMALLYFORWARD END PORTION OF THE SLEEVE, RECEIVED WITHIN SAID OPENING FORADJUSTABLE BEARING ENGAGEMENT WITH AND ON THE ADJACENT END OF SAIDBUSHING, AND, (E) A SECOND NUT THREADEDLY ENGAGED ON THE OPPOSITE ENDPORTION OF SAID SLEEVE, RECEIVED WITHIN SAID OPEN-